Been brewing beer for 5 years, never wine.
A family friend of mine makes a very “Efficient” wine.
He gets Concorde juice, straight from the vineyards here in the finger lakes, then adds 5lbs of table sugar to it…and lets it sit in the carboy for nearly a year…to his taste.
The juice is already so active, that he has to add the sugar 1 tablespoon at a time as it foams up to the top of the carboy and back down after each scoop.
This stuff is like drinking grape Hi-C from when I was a kid…not for everyone, but a bottle of it can make for an interesting evening once or twice a year…at night by the fire.
This may be way off topic for many of you who enjoy a more traditional wine (I prefer dry cabs myself)
But I was curious as to his method and approach…(No yeast)…in case I were to try it this fall when the crop comes in.
Similar story -
When I was little, I remember by Dad used to pick grapes from our vines, mash them, add sugar and he would put in a butter churn. He would stretch 'saran wrap" over the top, punch a hole for a tube and put the other end in a bottle of water for CO2 release/closed system.
He never added yeast - just the wild yeast from the grapes/skins. When finished, he would strain through cheese cloth.
He would always make a few gallons. As I got older, I seem to recall it was tasty but a bit on the sweet side.
I too have debated doing the same just to see how it would turn out.
You can certainly ferment with the wild yeast on the grape skins. The problem with doing this is that most of the yeast that are naturally occurring on the skins will have low alcohol tolerance, so the finished product will end up being very sweet. If this is what you want, then go for it!
A possible issue with concord grapes is their high acidity, so one approach to using them for making wine is to dilute with water until you’re at an appropriate T.A. level, and then add sugar back to a brix of 22-23. If you want something that doesn’t finish as sweet, treat it with Campden and ferment with your wine yeast of choice.